Add configuration to new appcast check

Library/Homebrew/cask/audit.rb

@@ -301,11 +301,16 @@ module Cask
     def check_appcast_contains_version
       return unless check_appcast?
       return if cask.appcast.to_s.empty?
+      return if cask.appcast.configuration == :no_check
 
       appcast_stanza = cask.appcast.to_s
-      appcast_contents, = curl_output("--max-time", "5", appcast_stanza)
+      appcast_contents, = curl_output("-L", "--max-time", "5", appcast_stanza)
       version_stanza = cask.version.to_s
+      if cask.appcast.configuration.to_s.empty?
         adjusted_version_stanza = version_stanza.split(",")[0].split("-")[0].split("_")[0]
+      else
+        adjusted_version_stanza = cask.appcast.configuration
+      end
       return if appcast_contents.include? adjusted_version_stanza
 
       add_warning "appcast at URL '#{appcast_stanza}' does not contain"\

Library/Homebrew/cask/dsl/appcast.rb

@@ -3,11 +3,21 @@
 module Cask
   class DSL
     class Appcast
+      ATTRIBUTES = [
+        :configuration,
+      ].freeze
       attr_reader :uri, :parameters
+      attr_reader(*ATTRIBUTES)
 
       def initialize(uri, **parameters)
         @uri        = URI(uri)
         @parameters = parameters
+
+        ATTRIBUTES.each do |attribute|
+          next unless parameters.key?(attribute)
+
+          instance_variable_set("@#{attribute}", parameters[attribute])
+        end
       end
 
       def to_yaml